1. Field of the Invention
The invention relates to methods and apparatus for reducing a dimension of a computer keyboard for storage or transport. The invention specifically relates to automatically opening a keyboard that folds into a small space for storage, such as that space available in a notebook or subnotebook computer.
2. The State of the Art
Manual typewriters had keyboards having large, widely spaced, keys to allow room for the mechanism of the typewriter and to allow users to strike the keys with the force required to actuate the mechanism.
Many features of todays computer keyboards are traceable to the characteristics of manual typewriters. Among these features are the QWERTY key layout and the size and spacing, of the keys. Many users of computer keyboards were trained on typewriters, or on computer keyboards incorporating the characteristics of typewriter keyboards. When these users purchase portable computers, they strongly prefer to purchase computers having a keyboard that, when in use, has similar key spacing, key size, and layout to the standard-size keyboards on which they were trained. These users also prefer to purchase computers with keyboards having keys that provide tactile feedback to the user, thereby assisting the user to properly position the fingers and exert appropriate keystroke force, such as keys that move over a distinct range that can be felt by users.
The standard QWERTY key layout of the alphabetic section of keyboards has a staggered arrangement of keys. The keys in the bottom row, "ZXCVBNM,/", do not line up with the keys in the second row, "ASDFGHJKL;'", which do not line up with the keys in the third row, "QWERTYUIOP[ ]", or those in the fourth, "1234567890-=.backslash." row. This staggered arrangement was dictated by the needs of mechanical typewriters, where each key was often attached to a separate lever, with all levers arranged in a single row. With typical key-modifier keys located at the ends of the key rows, a standard alphabetic keyboard section requires a space at least 10.5 inches by 3.5 inches.
Modern electronics allows production of portable computing devices that are smaller than standard size keyboards. For example, the Hewlett-Packard 95 series of portable computers, and many electronic organizers such as those by Casio, are portable computing apparatus too narrow for standard size, 10.5 inch or larger, conventional QWERTY keyboards. These machines often have keyboards with small, tightly spaced, keys that do not lend themselves to fast typing by users trained on standard keyboards.
U.S. Pat. No. 5,141,343, issued to me in August of 1992, describes a linearly compressible keyboard wherein the key pitch is reduced to permit storage of a full-sized keyboard in a smaller space than the 10.5 inches of a standard keyboard.
U.S. Pat. No. 5,187,644, issued to Crisan in February, 1993, describes a notebook computer wherein the keyboard has a pair of hinged flaps. These flaps hinge above the top of the key array, and fold inwardly. The flaps are supported when in use by foldout keyboard supports that extend from each flap to notches on the side of the computer body. The flaps of Crisan have numeric pad and function keys, with the alphabetic keys remaining in a center section. Crisan fails to disclose apparatus for automatically deploying his keyboard from the storage position into the operational position.
U.S. Pat. No. 5,267,127, issued to Pollitt in November of 1993, describes a keyboard fabricated in two sections, equivalent to a keyboard cut through the QWERTY section of the keyboard. These sections are pivoted together at the top of the keyboard. The pivot joint slides in a track on the upper surface of the notebook computer. For use, the sections are aligned to form an array like a standard keyboard, with the pivot slid to the rear of the computer. For storage, the sections remain in the same plane, each rotated ninety degrees with the pivot slid to the front of the computer top. Pollitt fails to disclose apparatus for automatically deploying his keyboard from the storage position into the operational position.
U.S. Pat. No. 3,940,758, issued to Margolin in February of 1976, describes a keyboard for a calculator that is fabricated in three sections. The Margolin keyboard includes a QWERTY section that is divided into two portions. Each section of Margolin's keyboard has an electrical connector that mates with the adjoining section when the three sections are arranged in line in operative position. The sections of Margolin are interconnected by a linkage. This linkage permits the keyboard sections to be separated, and stacked vertically. Margolin, does not suggest that the keys of the sections be retained by a latch in compressed position for storage, and does not disclose automatic deployment of the keyboard into operative position.
IBM has introduced the Thinkpad model 701C notebook computer. This computer has a keyboard divided into a first and a second section along a line having the appearance of a stairstep. A horizontal dimension of the keyboard is reduced for storage by shifting the second section of the keyboard backwards relative to the first section until its keys clear the adjacent steps of the first section, whereupon the second section is shifted horizontally to reduce the overall horizontal dimension of the keyboard. Both sections of the keyboard move relative to the computing device case, extending equally beyond the case in operative position, while fitting within the case in storage position. When the keyboard is deployed for operation, the second section is shifted in a reverse order and direction relative to the first section. The two sections of keyboard remain in the same plane in both storage and operative positions. Shifting of the second keyboard section relative to the first keyboard section is driven by a linkage coupled to the lid hinge, such that as the lid is raised the keyboard is deployed and as the lid is lowered the keyboard is moved to storage position. The inventor believes that no motors or springs are used to deploy the keyboard of the Thinkpad 701C, and is unaware of any latches for retaining the keyboard sections of the Thinkpad in operative position.
Thicknesses of keyboards from key tops to the bottom of the keyboard vary, but is frequently greater than a centimeter. Key travel, the distance that a key moves when pressure is applied, is usually from two to four millimeters, with 2.5 to 3.5 millimeters being common.
U.S. Pat. No. 4,879,698, issued to Langberg in 1989, teaches a polymeric piezoelectric actuator usable for producing vibrations in the 250-300 Hz range that may be felt with the fingertips.